Resumo AbstractQuality assessment of Eucalyptus grandis seedlings using morphological parameters. The present work had as objective determines the index of Dickson's quality (IDQ) and its relation to the morphologic variables in Eucalyptus grandis W. Hill ex Maiden seedlings produced in different treatments. The experiment was driven in the agronomic nursery of the Center of Superior Education North of Rio Grande do Sul (CESNORS), in experimental design of randomized complete block. Four treatments were tested, that involved two volumes sizes (50 and 90 cm³) and two levels of density of plants in the tray. It evaluated height of the aerial part, diameter of the lap, mass dries of leaves, mass dries of the stem, mass dries of the aerial part, mass dries of root, mass total drought (MST), foliar area (AF) and the index of Dickson's quality (IDQ). The size of the containers and the density of the seedlings in the tray had significant influence in growth of the seedlings along the time, putting limits to the volume of exploitable substratum and generating competition for space by the plants. All the appraised variables correlated significantly and IDQ revealed high index with MST. The treatments with container of volume 90 cm³ were the ones that presented the best IQD, resulting in seedlings of good quality capable to support the adverse conditions of the field.

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RESUMO -Este trabalho teve como objetivo determinar o poder calorífico superior (PCS) das árvores e a massa específica básica ponderada (ρ b pond ) da madeira de Acacia mearnsii De Wild, Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth e Ateleia glazioviana Baill distribuídas em diferentes espaçamentos em plantio: 2,0 x 1,0 m; 2,0 x 1,5 m; 3,0 x 1,0 m; e 3,0 x 1,5 m, nas idades de 1 e 3 anos. O estudo foi conduzido em um experimento localizado no Município de Frederico Westphalen, RS, em delineamento experimental de blocos completos casualizados com três repetições, no esquema de parcelas subdivididas. A determinação do PCS das árvores foi realizada a partir da ponderação dos valores obtidos em cada compartimento (madeira, casca, galho e folha), por meio de bomba calorimétrica. A determinação da ρ b pond foi realizada a partir da ponderação dos valores verificados dos discos coletados em diferentes posições ao longo do tronco, usando-se o método da balança hidrostática e massa seca. O PCS de todas as espécies no primeiro ano após o plantio foi superior ao do terceiro ano, destacando-se a Acacia mearnsii com as maiores médias. A ρ b pond não apresentou tendência sistemática de aumento ou redução ao longo do tempo e as espécies Acacia mearnsii e Ateleia glazioviana, os maiores valores. Os diferentes espaçamentos de plantio não induziram a variação do PCS e da ρ b pond nas espécies estudadas, não sendo verificada tendência sistemática positiva ou negativa em relação ao espaço vital proporcionado pelo espaçamento.Palavras-chave: Propriedade da madeira; Energia da biomassa; Espaçamento de plantio. INFLUENCE OF SPACING ON ENERGY CHARACTERISTICS OF TREE SPECIES ON SHORT ROTATION PLANTING ABSTRACT -This study aimed to determine the higher heating value (PCS) of trees and basic density weighted (ρ b pond ) of wood of

Sugarcane (Sacharum officinarum L.) monocropping has had a great socio-economic and environmental impact in Brazil, and agroforestry systems have been considered as an alternative for more sustainable production; however, there is a lack of field research under such conditions. The aim of this study was to evaluate the growth rates, radiation use efficiency and yield traits in sugarcane cultivated in the understory of Aleurites fordii, in two agroforestry arrangements and monocropping systems. A field experiment was conducted from July 2015 to June 2016 in the city of Frederico Westphalen, Rio Grande do Sul, Brazil. The radiation use efficiency, assimilate partitioning, leaf area index, absolute growth rate, net assimilation rate, number of tillers, plant height, % of intercepted solar radiation, extinction coefficient, and yield in each system was evaluated. In agroforestry systems, the dynamic interactions between multiple plant species change with the time and can result in unique microclimates. The use of agroforestry systems in 12 x 12m arrangements should be prioritized because it enables greater yields and radiation availability in the understory. This study sought to provide new sustainable alternatives for farmers in order to increase the diversification of the rural property and maintain the preservation of existing agroecosystems.An Acad Bras Cienc (2018) 90 (4) 3266FELIPE SCHWERZ et al.

Soybean (Glycine max L.) monocropping have had a great socioeconomic and environmental impact on the world and agroforestry systems has been considered an alternative for more sustainable production. The aim of this study was to evaluate the effect of different arrangements of agroforestry systems of the species E. urophylla x E. grandis and P. dubium and the pruning of the trees on the dynamics of solar radiation and soybean yield. A field experiment was conducted in Southern Brazil. In order to achieve the objective of the study, the solar radiation transmissivity and the productive performance of the soybean were evaluated. In this study, the soybean yield was determined by the arrangement of the agroforestry system and forest species utilized. The soybean crop cultivated in the understory of the P. dubium trees showed the highest yield response. The use of silvicultural practices for the management of forest species should be considered to generate the balance of the productive system. In this context, tree pruning is a viable side for agroforestry systems, as it promotes an increase in the incidence of solar radiation in the understory, resulting in an increase in soybean yield, especially when integrated with P. dubium.